(a) Technical Field
The present invention relates to an apparatus for purifying asbestos-contaminated soil which removes asbestos from soil contaminated with asbestos so as to purify the soil, and more specifically, to an apparatus for purifying asbestos-contaminated soil capable of increasing the removable efficiency of removing the soil by applying a drop method, facilitating the scattering of asbestos by extending the drop time of soil, and improving the separation efficiency of the asbestos from the contaminated soil by preventing the generation of eddies in the soil.
(b) Background Art
Generally, asbestos refers to six kinds of silicate mineral having a fibrous texture. Specifically, asbestos collectively refers to chrysolite, amosite, crocidolite, anthophilite, themolite, and actinolite. The World Health Organization designates asbestos as a class 1 carcinogen. It is known that, if asbestos is inhaled through the respiratory organs, it is likely to cause lung cancer, malignant mesothelioma, and pulmonary asbestosis after ten to forty years of an incubation period.
Recently, 125 million workers have been exposed to the asbestos throughout the world. It is estimated that approximately ninety thousand workers die every year from asbestos related illnesses such as asbestosis, lung cancer, malignant mesothelioma, or the like.
Specifically, there are several tens of asbestos contaminated patients per 100,000 people every year in the Metsovo region of Greece, the Metintas, Baris, and Yazicioglu region of Turkey, the New Caledonia region, or the like.
In Korea as well, several tens of asbestos mines were developed by the Japanese prior to liberation. Also after liberation, the development of asbestos mines was at its highest level during the 1980s when mining continued along with economic development.
Therefore, it is estimated that there are many regions around asbestos mines in Korea which have been contaminated. Recently, cases of asbestos sufferers have been reported in the region surrounding closed asbestos mines of the Gwangcheon and Boryeong areas of Chungchungnamdo in Korea.
As mentioned above, ‘Guidelines for Management of Soil Environments for Asbestos Affected Regions’ was prepared by July of 2010 after the harmfulness of asbestos was considered. When the asbestos level of the soil is less than 0.25%, with PLM 400 point computation method as criteria, it is considered to be safe. If the asbestos level is 1% or more, soil restoration should be conducted. When the level is ranging from 0.25% to 1%, hazard evaluation should be conducted.
In addition, the above guideline also sets asbestos level criteria in groundwater and indoor air, and, as such, the management of asbestos has started in earnest.
Thus, it is necessary for purifying the contaminated soil based on the wide ranging survey of asbestos-contaminated soil which does not satisfy the above environmental standards. However, the purification and restoration techniques for the contaminated soils remain merely at their beginning stages.
A number of methods for recovering the asbestos-contaminated soil are proposed in the related art. First, there is a so called ‘no action’ method, which entails closing down of the site for areas suspected of asbestos pollution without taking any measures. Second, there is a method of limiting people's movements around areas where an examination of the soil finds that it contains asbestos. Third, there is a mud capping method, where one caps with mud so as to prevent asbestos containing substances on polluted sites from scattering into the air. Other methods include afforestation, microorganism treatment, reclamation, or the like. However, these methods not only do not work well in Korea and lack economic benefits due to the high cost thereof but also entail insufficient effectiveness since they do not fundamentally remove asbestos.
A key issue is such that, asbestos-contaminated soil in the Korean environment exists on sites which are close to people's everyday activity such as residential areas or farms surrounding mines and the like. It is not possible to limit the utilization of such sites or close them down.
The mud capping or reclamation after excavation method is not economical, because it requires a large amount of clean soil. Especially mud capping cannot be seen as a fundamental restoration method, because asbestos-contaminated soil is exposed to air again from weathering after a certain duration of time elapses. Microorganism treatment requires an extended duration of time and has a problem of effecting change to the environment of native microorganisms. Heat treatment also lacks economic feasibility and efficacy thereby deteriorating the reliability thereof. Further, conventional apparatuses for purifying the contaminated soil include: excavating soil, conveying it to a purification apparatus for treating the same, and returning it to the original site. However, there is a problem in that the entire process is long and lacks economical efficacy.
Therefore, there is a need to develop an apparatus for purifying asbestos-contaminated soil capable of sufficiently removing asbestos onsite and recovering the soil economically. The present inventors applied for a patent on Oct. 31, 2011 and registered a “mobile apparatus for purifying asbestos-contaminated soil” (see Korean Patent Registration Publication No. 10-1080177). The apparatus for purifying asbestos-contaminated soil disclosed in the above patent includes a main chamber provided with a space configured to temporarily receive the polluted soil to separate asbestos from the soil, an agitating means configured to agitate soil in the main chamber to scatter the asbestos, a collection chamber into which the scattered asbestos from the soil is transferred to collect the asbestos, and a collection means configured to collect asbestos in the collection chamber.
The technological characteristics of the above patent entail excavating soil with a tractor or other machines and conveying it on a belt. During this process, asbestos is separated from soil as it is scattered with a blower and is separated from the soil.
However, it is difficult to efficiently separate the asbestos from soil which contains moisture and is strongly adhered to the soil particles by simply utilizing the stirring from the tractor and the air of a blower.
Also, in order to place the asbestos on a filter using a water sprinkler, there is a need to stably and continuously provide water. Therefore, it is difficult to use the apparatus in an area where sufficient water cannot be provided for a sprinkler or the like.